According to the law of dominance, what is true about dominant alleles?

Dominant alleles are characterized by their ability to express themselves phenotypically in the presence of one or more alleles. When an organism carries a dominant allele, it will be the trait that is visibly represented in the organism's phenotype, regardless of the presence of a recessive allele. This means that even if the organism has one dominant allele and one recessive allele for a specific trait, the dominant trait will be the one that is shown. This concept is foundational in genetics, illustrating how certain traits can dominate over others when interacting with different alleles.

The other options do not accurately reflect the nature of dominant alleles. For instance, dominant alleles are not recessive; they produce visible traits when present. Additionally, dominant alleles do indeed affect traits, as their presence leads to the expression of specific characteristics. Lastly, dominant alleles cannot be masked by recessive alleles in a heterozygous condition, which is a key aspect of their definition.